【目的】 本研究旨在初步探索粘虫的抗寒力，以期能够为粘虫Mythimna separata（Walker）预测预报提供依据。【方法】 测定粘虫不同发育期、不同光周期下的过冷却点，并计算虫体含水量；测定0、5、10℃下处理不同时间时粘虫老熟幼虫和蛹的死亡率。【结果】 蛹的过冷却点、结冰点和含水量最低，并且粘虫不同发育期的过冷却点、结冰点和含水量差异显著（P<0.05）；不同光周期下粘虫的过冷却点和含水量并无显著差异；在0、5、10℃条件下，粘虫老熟幼虫和蛹的死亡率均随着温度降低而增加，老熟幼虫的死亡率均小于蛹；雌雄蛹对低温的抵抗力有差异，温度较低并且处理时间较短时，对雌蛹的死亡率影响较大，而温度稍高或处理时间较长时，对雄蛹的死亡率影响较大。【结论】 粘虫蛹的抗寒力最强，低温以及低温的持续时间影响蛹的性比以及老熟幼虫和蛹的死亡率，光周期对粘虫的抗寒力无显著影响。

 [Objectives]  To investigate the cold hardiness of the beet armyworm Mythimna separata (Walker) in order to provide a basis for predicting outbreaks of this pest. [Methods]  We measured the super-cooling point (SCP), freezing point (FP) and water content of armyworms at different developmental stages that were raised under different photoperiods. Armyworms overwinter as pupae and mature larvae in some regions, so pupae and mature larvae were measured at 0, 5 and  10℃, respectively. [Results]  1. The SCP, FP and water contents of pupae were lowest, and there were significant differences in the SCP, FP and water content of different development stages (P<0.05), but not different photoperiods. 2. The survival rate of larvae and pupae varied greatly with temperature. Mortality increased as temperature decreased from 10℃ to 0℃ at intervals of 5℃, regardless of developmental stage. The mortality of pupae was higher than that of mature larvae. The susceptibility of male and female pupae to low temperature differed; female pupae had higher mortality at lower temperatures when the exposure time was shorter. [Conclusion]  The cold hardiness of pupae was highest, and the sustained duration of low temperature influenced the sex ratio of pupae and the mortality of overwintering individuals, thus affecting the dynamics of the population in the following year. Photoperiod had no influence on the cold hardiness of armyworms.